Magnetic resonance imaging apparatus

ABSTRACT

A magnetic resonance imaging apparatus includes a magnet having a two poles and a wall connecting the poles; the poles delimiting a patient-imaging space; and a table which is slidably connected to one of the two poles between the two poles and which table extends substantially parallel to the two poles; a drive for displacing the table relative to the magnet; a lock for locking the table in a selected position relative to the magnet; a drive for rotating the magnet about the axis; the table connected to the magnet such that the table rotates with the magnet when the magnet rotates about the axis; the magnet and the table being rotatable from a position in which the poles and the table are horizontal to a position in which the table and the poles are vertical.

BACKGROUND OF THE APPLICATION

1. Field of the Invention

The invention relates to a magnetic resonance imaging apparatus, andparticularly to a multipurpose dedicated imaging apparatus havingimproved features for imaging the region of the vertebral column.

2. Description of the Related Art

Imaging the vertebral column may require the possibility of bringing thepatient in an upright position in order to have the vertebral columnloaded by the weight of the patient. In the normal laying down positionof the patient on a bed or table having an horizontal orientation, thevertebral column will be in an unloaded and ideal condition. Thus, mostpathologies may not arise clearly and the examination will lead tounclear results or to negative results despite the fact that the patientis showing typical symptoms of a disease of the vertebral column.

Actually known magnetic resonance imaging apparati use so called totalbody scanners which magnetic structure houses the entire body or aconsiderable part of it inside the patient examining space defined bythe magnetic structure.

U.S. Pat. Nos. 6,414,490 and 6,504,371 disclose magnetic resonanceimaging apparatus of the above mentioned kind. The magnetic structure isdesigned to generate a horizontal magnetic field. The patient is broughtinside the examining space by means of a patient positioning devicewhich is a bed or table mounted on a carriage, which bed or table can befurther tilted around horizontal axis for giving different orientationsto the bed or table with respect to the vertical direction. Furthermore,in order to focus the region of the patient to be imaged, the bed ortable or carriage may be associated with an elevator which displaces thepatient up and down relative to the examining space between the poles ofthe magnetic structure.

The actual devices are very big, heavy, and expensive. Big and heavymagnetic structures have problems of installation, since the room wherethe imaging apparatus has to be installed must necessarily have a floorwhich can support the weight of the imaging apparatus. Furthermore, theroom must be sufficiently big to permit installation.

The patient positioning device is also relatively expensive due to thetiltable or swingable bed or table and due to the necessity of anelevator for displacing the patient relative to the imaging space in themagnetic structure.

On the other hand, even if the anatomic region of the vertebral columnis a very large one, usually examination through imaging is carried outfor only a certain specific part of the vertebral column.

OBJECTS AND SUMMARY

An object of the present invention is to provide for a magneticresonance imaging apparatus which has a smaller magnetic structure thanthe conventional so called total body apparatus and which allowsnevertheless imaging of the vertebral column under various conditions.

A further aim is to provide for such a magnetic imaging apparatus whichhas simpler and less expensive means for positioning the patient in theexamination space of the magnetic structure.

A further object of the present invention is to provide for a magneticresonance imaging apparatus which can be used also for examinations ofother anatomic regions of the body of the patient, by allowing in asimple way to displace the patient relative to the examination space inthe magnetic structure in order to bring the desired anatomic region ora certain limited region thereof in the examination space.

One embodiment of the present invention includes a magnetic resonanceimaging apparatus comprising a magnet having a two opposite and spacedapart poles and a column or wall transverse to the poles and connectingthe poles; the poles defining two opposite walls delimiting apatient-imaging space, the two opposite walls extending alongsubstantially parallel planes which are substantially perpendicular to avertical plane; and a patient positioning table which is slidablyconnected to one of the two poles in a position between the two polesand which table extends substantially parallel to the two oppositepoles; the table being slidable with respect to the magnet in adirection parallel to a longitudinal axis of the table; a drive fordisplacing the table relative to the magnet; a lock for locking thetable in a selected position relative to the magnet; the magnet beingsupported rotatably along a central horizontal axis of the transversewall or column; a drive provided for rotating the magnet about the axis;the table being connected to the magnet such that the table rotates withthe magnet when the magnet rotates about the axis; the magnet and thetable being rotatable from a position in which the poles and the tableare substantially horizontal to a position in which the table and thepoles are substantially vertical, and vice versa; and the rotation ofthe table and the magnet are locked together by the lock.

Another embodiment of the present invention includes a method formagnetic resonance imaging with a magnetic structure having two oppositepoles spaced apart one from the other and oriented substantiallyperpendicular to a vertical plane and defining a patient imaging space;and a table for a patient secured to one of the two poles in a slidableway in a longitudinal direction of the table relative to the magneticstructure and between the two poles of the magnetic structure, the tablebeing oriented parallel to the poles, the table having a footrest at oneend thereof, the magnetic structure and the table being rotatabletogether around an axis which is transverse to a longitudinal axis ofthe table and parallel to the table. The method comprises:

rotating the magnetic structure with the table to a patient positioningposition in which the table is substantially horizontal;

sliding the table to an end position, in which a part of the table isoutside the magnetic structure;

arranging the patient on the table in a lying down position;

sliding the table along its longitudinal axis relative to the magneticstructure until the magnetic structure is correctly centered with a partof the patient's body to be examined;

locking the table relative to the magnetic structure together with thetable in a position in which the table is not horizontal or vertical;

carrying out an imaging procedure;

rotating the magnetic structure together with the table to a position inwhich the table is substantially horizontal; and

sliding the table to one of two positions in which a part of the tableis outside the magnetic structure and letting the patient step down fromthe table.

Another embodiment of the present invention includes a method forcarrying out magnetic resonance imaging with providing a magneticstructure having two opposite poles spaced apart one from the other andoriented substantially perpendicular to a vertical plane and defining apatient imaging space; and a table having a footrest at one end andslides for engaging guides for a longitudinal displacement of the table;and a table supporting structure which has wheels and which iscompletely independent from the magnetic structure, one of the poles ofthe magnetic structure and the table supporting frame have identicalguides with which the slides of the table are adapted to engage. Themethod comprises:

rotating the magnetic structure such that the guides for the table arehorizontal and aligning the table supporting frame with the guides ofthe table supporting frame aligned with the guides on the pole of themagnetic structure; lying the patient down on the table;

sliding the table along a longitudinal direction thereof away from thetable supporting frame and against the pole having the guides andengaging at the same time a free end of the slides of the table with theguides on the pole;

sliding the table with the patient on the table until the table iscompletely disengaged from the table supporting frame and engaged withthe pole of the magnetic structure;

sliding further the table along its longitudinal axis relative to themagnetic structure until the magnetic structure is correctly centeredwith a part of the patient's body to be examined;

supporting the magnetic structure and the table in such a way as to berotatable together around an axis which is transverse to thelongitudinal axis of the table and substantially parallel to the table;

locking the table relative to further sliding and rotating the magneticstructure together with the table with the patient on it in a positionin which the table is not horizontal;

carrying out the imaging procedure;

rotating the magnetic structure together with the table back to aposition in which the table is substantially horizontal;

sliding the table away from the pole of the magnetic structure onto thetable supporting frame.

Another embodiment of the present invention includes a method forcarrying out magnetic resonance imaging with a magnetic structure havingtwo opposite poles spaced apart one from the other and orientedsubstantially perpendicular to a vertical plane and defining a patientimaging space; and a table for a patient to one of the two poles in aslidable way in a longitudinal direction of the table relative to themagnetic structure and between the two poles of the magnetic structure,the table being oriented substantially parallel to the poles; themagnetic structure and the table being rotatable together around an axiswhich is transverse to the longitudinal axis of the table and parallelto the table. The method comprises:

rotating the magnetic structure together with the table in a position inwhich the table is not horizontal;

providing a seat plate secured at an angle to the table;

sitting the patient down on the seat plate;

carrying out the imaging procedure; and

letting the patient step out of the magnetic structure.

BRIEF DESCRIPTION OF THE DRAWINGS

The magnetic resonance imaging apparatus and the advantages thereof willappear more clearly from the following description made with referenceto an embodiment which is illustrated in the annexed drawings whichdrawings illustrate:

FIG. 1 is a schematic frontal view of an embodiment of a magneticresonance imaging apparatus according to the invention.

FIG. 2 is a schematic lateral view partly sectioned of the apparatusaccording to FIG. 1.

FIGS. 3 to 6 are simplified frontal views of an embodiment of theapparatus according to the invention in its position with the tableoriented along the horizontal plane and in different relative positionsof the table with respect to the magnetic structure.

FIGS. 7 and 8 are perspective views of an embodiment of the apparatusaccording to the present invention with the magnetic structure and thetable in the position in which the table is horizontal and in theposition in which the table is vertical.

FIG. 9 illustrates a lateral view of an embodiment of the apparatusaccording to the present invention in which a seat is associated to thetable.

FIG. 10 illustrates a frontal view of an embodiment of the magneticresonance imaging apparatus according to the present invention incombination with a separate supporting frame for the table.

FIG. 11 shows a partial section of a enlarged particular of one slideand guide of the table according to one embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the Figures, particularly FIGS. 1 and 2, a magneticresonance imaging apparatus according to an embodiment of the inventionis schematically illustrated.

The magnetic resonance imaging apparatus comprises a supporting element1 in the form of a vertical wall. A magnetic structure 2 is secured tothe supporting element 1 in a overhanging way. The magnetic structure 2comprises two opposite poles 102, 202 which are oriented perpendicularlywith respect to the supporting wall 1, and which are connected togetherin a spaced apart relationship by means of a column or wall 302 whichextends parallel to the supporting wall 1 and which is secured to thewall by means of a shaft 3 perpendicular to the supporting wall 1 and tothe transverse connecting wall 302 of the magnetic structure 2. The axisof the shaft 3 which is rotatable in a housing in the supporting walland is also parallel to the poles 102, 202 and perpendicular to themagnetic field generated between them. The axis of the shaft 3 iscoincident with the center of symmetry of the wall 302 of the magneticstructure, although this is not a necessary feature in order to ensurethe functions of the present magnetic resonance imaging apparatus.

A coaxial frontally toothed crown 101 on the supporting wall 1cooperates with a driving pinion 4 which is driven by a motor 5 by meansof a transmission 6. Thus, the motor 5 can cause the rotation of themagnetic structure 2 around the axis of the shaft 3 relative to thesupporting wall 1. Although the frontally toothed coaxial crown 101 isillustrated mounted on the supporting wall 1, the same result could bereached by providing the toothed crown on the wall 302 of the magneticstructure and the motor 5, the transmission 6 and the pinion 4 on thesupporting wall. This solution would avoid elements on the wall 302which could cause disturbance to the circulation of the magnetic fluxwithin said wall 302.

A table 7 is slidably mounted in a direction parallel to itslongitudinal axis on the lower pole 102 of the magnetic structure. Asused herein, the term “table” may be a bed, bed plate, table plate, orother flat surface on which a patient may lie for purposes ofexamination. The table or bed plate 7 is oriented with its longitudinalaxis perpendicular to the axis of the shaft 3 and parallel to the wall302 of the magnetic structure 2.

The table 7 is supported slidably in its longitudinal direction by meansof a combination of guides and slides, motorized means being alsoprovided for deriving the displacement of the said table 7 relative tothe magnetic structure 2.

In the present embodiment, two longitudinal slides 107 are providedunderneath the table 7 and are secured thereto. The slides 107 extendalong opposite longitudinal sides of the table 7 are slidably engaged inguides 8, 8′ provided at the transverse ends of the lower pole 102 ofthe magnetic structure.

A combination of a longitudinal rack secured to the table 7 and a piniondriven by a motor ensures a motorised displacement of the table along itlongitudinal axis and in both directions.

As illustrated, the racks may be formed also by the one or both slides107, a surface of which has a toothed longitudinal region which engageswith a corresponding pinion 4 housed in a recess of the one or bothguides 8, 8′. The pinion or pinions 4 are driven by a motor 9 through ashaft 104. See FIGS. 2 and 11.

As shown in FIG. 11, the slides 107 and the guides 8, 8′ have a crosssection which forms a mutual undercut for avoiding the slipping out ofthe slides 107 from the guides when the magnetic structure is rotatedtogether with the table 7 from the horizontal position of the table to avertical position.

Many different designs of the slides and of the guides may be chosen.One simple solution illustrated in FIG. 11 comprises a lateralcontinuous tooth 207 on each slide 107 which engages a lateralcontinuous slot 108 in the corresponding lateral wall.

Furthermore, nonillustrated releasable locking means of the table 7relative to the magnetic structure 2 are provided. This locking meansmay consist in the combination of the rack and pinion mechanism whichmight be of the nonreversible kind if the motor is deenergised.Alternatively, mechanical locking means, such as releasable lockingteeth engaging the rack, may be provided which means may be drivenalternatively in an active position of engagement and in an inactiveposition of disengagement by means of manual, electric or other kinds ofactuators.

According to a further feature, the table 7 may be also slidable in adirection transverse to its longitudinal axis, i.e., in a directionperpendicular to the wall 302 of the magnetic structure 2. This may beobtained in a similar way as the method described with reference to thelongitudinal displacement of the table 7.

According to the illustrated example, the guides 8, 8′ on each side ofthe pole 102 are arranged on a transverse slide 10 which engages atransverse guide 11. The transverse guide and slides may have across-section with mutually engaging undercuts as described withreference to the longitudinal guides and slides and according to FIG.11. The displacement in the transverse directions may be driven by amotor 9′ by means of a combination of racks and pinions as described indetail with reference to the longitudinal guides and slides.

Also for the transverse displacement of the table 7 releasable lockingmeans may be provided which may be activated or deactivated as describedwith reference to the releasable locking means for the longitudinaldisplacement of the table 7.

Thanks to the above disclosed construction, the magnetic resonanceimaging apparatus according to the present invention allows positioningof the patient on the table 7 when the magnetic structure with the tableare rotated in an horizontal position of the poles 102, 202 and of thetable 7.

In order for the patient to lie on the table 7, the table 7 may bebrought to its maximum longitudinal displacement, as illustrated in FIG.3. After the patient has taken place correctly on the table, the tablemay be displaced relative to the magnetic structure 2 in itslongitudinal direction or if provided also in its transverse direction.FIGS. 4 to 6 illustrates different relative positions of the table 7with respect to the magnetic structure 2.

The FIGS. 3 to 6 also clearly illustrate that the magnetic resonanceimaging apparatus according to the present invention allows not only tocarry out useful images of the vertebral column but due to the fact thatthe table 7 might be displaced continuously in longitudinal andtransverse directions, the patient can be brought every time with adifferent anatomic region in the examination space formed between thetwo poles 102, 202, thus allowing different kinds of examinations.

In order to reduce the load on the guides and slides of the overhangingtable 7 at its extreme positions (FIGS. 3 and 6), the table might beprovided at one or both of its ends with a couple of wheeled legs 15 asis shown in FIG. 1. This allows an extraction of the table from themagnetic structure for almost its entire length, provided the endwithout the wheeled supporting legs will rest engaged for a terminallength with the magnetic structure.

Once the patient is on the table 7, the magnetic structure 2 can berotated together with the table 7 through an angle of 90°. In thisposition the table is vertical and the patient is in an uprightposition. In order to allow the patient to reach the upright position,at the end of the table associated with the feet a footrest 12 isprovided. This footrest may be fixed or it may be formed by a platewhich is secured in position to the table after having positioned thepatient or the footrest may be formed by a prolongation of the table 7which is hinged to the table 7 in such a way as to be brought andblocked alternatively in the overhanging position and in a positionparallel to the rest of the plate 7.

As is clear from the FIGS. 7 and 8, the magnetic structure and the tablemay be rotated for an angle less than 90°, thus modulating the load onthe vertebral column of the patient due to the weight of the patientitself.

Once imaging has been carried out, the magnetic structure 2 and thetable 7 can be rotated again in the position where the table 7 ishorizontal. The table can then be displaced to one of its end positions,and the patient can leave the apparatus.

According to a further improvement illustrated in FIG. 10, a separatesupporting structure 20 may be provided for the table 7. This separatesupporting structure is formed by a frame having wheeled legs. Thesupporting structure 20 is provided on its top with guides 8″ which areidentical in position and cross section to the guides 8,8′ for thelongitudinal slides 107 of the plate 7. Thus by aligning the guides 8″on the separate supporting structure 20 for the plate 7 with the guides8, 8′ of the pole 102, the table 7 may be transferred by longitudinaldisplacement from the said supporting structure 20 to the guides 8, 8′on the pole 102, and vice versa. Thus, the patient might be prepared forexamination on a table outside the magnetic structure while anotherpatient is subjected to examination in the apparatus.

Because the plate 7 can be inserted in the magnetic structure from oneside and extracted from the magnetic structure on the opposite side, andby providing at least two plates 7 with at least two supporting frames20 one for each plate, it is possible to control the traffic of patientsto be examined.

In such a case, the table with a patient who has just finished theexamination is extracted from the magnetic structure, for example, fromthe left hand end of the structure 2 of FIG. 10, while the table 7 witha following patient is inserted in the magnetic structure from the righthand side of the magnetic structure 2.

This solution also allows preparation of the patient for examination ona table outside the magnetic imaging apparatus so that a patient can beprepared for examination while another patient is examined in theapparatus. Providing a disengagement of the bed or table from themagnetic structure from one side of the magnetic structure and theengagement of the following bed or table with the magnetic structure onthe opposite side of it the apparatus is even more rational regardingthe traffic of patient.

By providing the supporting structure of the table 7 with guidesoriented perpendicularly to the longitudinal axis of the table 7 itself,the insertion or extraction of the table 7 in and from the magneticstructure 2 can also be carried out in a transverse direction of thetable 7.

According to a further feature which is shown in FIG. 9, a seat plate 21may be provided. The seat plate 21 may be secured directly to the table7 at different heights or there might be provided a supporting rod 22which is secured parallel to the plate 7 to the plate itself or to themagnetic structure. The rod 22 carries an overhanging seat plate, theseat plate being secured to the rod by means of a slide engaging therod, releasable locking means being provided for locking the seat plate21 at a desired height.

Thanks to the above embodiments of the magnetic resonance imaging deviceaccording to the invention, a method for carrying out the examinationparticularly of the vertebral column of a patient can be defined. Anadvantage of this method lies in the fact that a simple and notoverdimensioned magnetic structure and patient supporting unit isneeded.

The magnetic structure of the imaging apparatus is preferably of the socalled dedicated kind, forming a patient imaging space which is at leastshorter than the mean height of adult patients. Such magnetic structuresare relatively light and less costly than total body magnets or similarmagnets. Furthermore such dedicated magnetic structures are handy andcan be supported in a displaceable manner without taking into accounthigh expenses for the means which allow the displacement of the magneticstructure.

In the case of magnetic structures of the dedicated kind, the table ortable plate has a length which is greater that the correspondingdimension of the poles of the magnetic structure and a width which is ofthe order of the corresponding dimension of the poles.

An embodiment according to the invention allows also a simpler and lessexpensive patient positioning, due to the fact that the table and themagnetic structure are supported in a way as to be rotated together, thepositioning of the patient, by sliding the table relatively to themagnetic structure is carried out in the condition of rotation of themagnet and of the table in which the table is horizontal.

Thus, the means for allowing the sliding displacement of the table aswell as the means for driving the displacement of the table can be ofreduced strength and of reduced power with respect to the solutiondisclosed in the above mentioned prior art documents. This on the otherhand leads to lower costs, weight reduction and a slighter and simplerconstruction.

Sliding the table with the patient for positioning the patientrelatively to the examining space when the table is horizontal orsubstantially horizontal means that the effects of the weight of thepatient on the sliding movement are reduced to the inertia and to thefriction, while the gravitational effects are suppressed.

As it might appear clearly, there is no limitation in the position ofthe patient relative to the magnetic structure and to the examiningspace in it.

According to a further improvement, the table might also carry outdisplacements which are in the transverse direction relative to itslongitudinal axis.

Due to the fact that the bed or table is long with respect to thecorresponding dimensions of the magnetic structure, the patient may laydown on the table or bed without any difficulty since the table or thebed might be displaced in one of the two opposite end positions in whichit extends out from the magnetic structure for a very relevant part.

It is also to be noted that the bed or table can also be designed in amanner as to be used also in other diagnostic devices or apparati.

Providing not only a footrest, but also a seat plate which might beformed by a section of the bed or table allows examinations of thepatient also in a sitting position.

In this case there are two options for the patient to enter the magneticstructure. According to a first option the patient enters the magneticstructure with the bed or table in the horizontal position and in lyingthe patient takes a lying position lying on the bed or table and againstthe seat. The magnet and the table can be rotated to a substantiallyvertical position of the bed or table and thus moving the patient to asitting position. According to a second option, the patient enters themagnetic structure when the bed or table and the magnet are rotated inthe vertical position of the bed or table and stands on a footrest orsits down on a seat.

Relating the way of constructing the means for sliding the table and forreleasably locking it to the magnetic structure and also the means forrotating table and magnetic structure, the expert in the art is free tochoose any kind of known device, such as guides, slides, actuators etc.

One example of a method according to the present invention comprises thefollowing steps:

Providing a magnetic structure having two opposite poles spaced apartone from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

Securing a bed or table for the patient to one of the two poles in aslidable way in the longitudinal direction of the bed or table relativeto the magnetic structure and between the two poles of the magneticstructure, the bed or table being oriented substantially parallel to thepoles, the bed or table preferably having a footrest at one endcorresponding to the position of the patient's feet;

Supporting the magnetic structure and the bed or table so that themagnetic structure and the bed or table are rotatable together around anaxis which is transverse to the longitudinal axis of the bed or tableand parallel to the bed or table;

Rotating the magnetic structure with the table in a patient positioningposition in which the bed or table is substantially horizontal;

Sliding the bed or table in one of its extreme end positions, in whichthe part of the bed or table being outside the magnetic structure is amaximum;

Arranging the patient on the bed or table in a lying position;

Sliding the table or the table along its longitudinal axis relative tothe magnetic structure until the magnetic structure is correctlycentered with the part of the patient's body to be examined;

Locking the bed or table relative to a further sliding and rotating themagnetic structure together with the bed or table in a position in whichthe bed or table is not horizontal or perfectly vertical;

Carrying out the imaging procedure;

Rotating the magnetic structure together with the bed or table back in aposition in which the bed or table is substantially horizontal;

Sliding the bed or table again in one of the two extreme positions inwhich the part of the bed or table outside the magnetic structure is amaximum and letting the patient step down from the table.

Alternative to the phases of sliding the bed or table in one of theextreme positions in which the part of the table outside the magneticstructure is a maximum for letting the patient lie down on the plate orstep down from the plate, the bed or table may be completely disengagedfrom the magnetic structure and at the same time engaged in a slidablyway onto an independent and separate wheeled supporting frame.

Such an alternative embodiment comprises the steps of:

Providing a magnetic structure having two opposite poles spaced apartone from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

Providing a bed or table having at least slides for engaging guides fora longitudinal displacement of the said bed or table;

Providing a bed or table supporting structure which has wheels and whichis completely independent from the magnetic structure and/or the imagingapparatus;

Providing one of the poles of the magnetic structure and the bed ortable supporting frame with identical guides with which the slides ofthe bed or table can be engaged;

Rotating the magnetic structure in a position in which the guides forthe bed or table are substantially horizontal and aligning the table orbed supporting frame with its guides aligned with the guides on the poleof the magnetic structure;

Providing a bed or table supporting structure with a bed or tablearranged on it and letting the patient lie down on the said bed ortable;

Sliding the bed or table along its longitudinal direction away from thesupporting structure and against the pole having the guides and engagingat the same time the free end of the slides of the bed or table with theguides on the pole;

Sliding the bed or table with the patient on it until the plate iscompletely disengaged from the supporting frame and engaged with thepole of the magnetic structure;

Sliding further the bed or table along its longitudinal axis relative tothe magnetic structure until the magnetic structure is correctlycentered with the part of the patient's body to be examined;

Providing the bed or table with a footrest at one end corresponding tothe position of the patient's feet.

Supporting the magnetic structure and the bed or table in such a way asto be rotatable together around an axis which is transverse to thelongitudinal axis of the bed or table and parallel to the bed or table;

Locking the bed or table relative to a further sliding and rotating themagnetic structure together with the bed or table with the patient on itin a position in which the bed or table is not horizontal or perfectlyvertical.

Carrying out the imaging procedure;

Rotating the magnetic structure together with the bed or table back in aposition in which the bed or table is substantially horizontal;

Sliding the bed or table back away from the pole of the magneticstructure onto the supporting frame.

According to a further embodiment, the bed or table is transferred ontothe pole of the magnetic structure from the supporting frame and backfrom the pole on the said supporting frame after examination by slidingthe bed or table always in the same longitudinal direction of the bed ortable, so that a further step of the method includes displacing thesupporting frame from the first side of the magnetic structure at whichthe bed or table has been transferred to the pole to the second oppositeside of the pole and aligning the guides of the supporting frame withthe guides on the pole of the magnetic structure;

Sliding the bed or table further in the same direction of transfer fortransferring the bed or table with the patient on it from the pole againto the supporting frame.

The above mentioned method may provide a rotation of the magneticstructure together with the patient lying on it from the horizontalposition to a nonhorizontal position which in intermediate with respectto the horizontal position and to the vertical position.

A further embodiment of imaging may comprise the following steps:

Providing a magnetic structure having two opposite poles spaced apartone from the other and oriented substantially perpendicularly to avertical plane and defining a patient imaging space;

Securing a bed or table for the patient to one of the two poles in aslidable way in the longitudinal direction of the bed or table relativeto the magnetic structure and between the two poles of the magneticstructure, the bed or table being oriented parallel to the poles.

Supporting the magnetic structure and the bed or table in such a way tobe rotatable together around an axis which is transverse to thelongitudinal axis of the bed or table and parallel to the said bed ortable;

Rotating the magnetic structure together with the bed or table in aposition in which the bed or table is not horizontal or perfectlyvertical;

Providing a seat plate which is secured at an angle to the vertical bedor table;

Letting the patient sit down on the seat plate;

Carrying out the imaging procedure;

Letting the patient step out of the magnetic structure.

According to a further embodiment, each one of the alternative methodsmay further comprise the step of sliding the bed or table or the seatplate transverse to the longitudinal axis of the bed or table.

Although only preferred embodiments are specifically illustrated anddescribed herein, it will be appreciated that many modifications andvariations of the present invention are possible in light of the aboveteachings and within the purview of the appended claims withoutdeparting from the spirit and intended scope of the invention.

1. A magnetic resonance imaging apparatus, comprising: a magnet having a two opposite and spaced apart poles and a column or wall transverse to the poles and connecting the poles; the poles defining two opposite walls delimiting a patient-imaging space, the two opposite walls extending along substantially parallel planes which are substantially perpendicular to a vertical plane; and a patient positioning table which is slidably connected to one of the two poles in a position between the two poles and which table extends substantially parallel to the two opposite poles; the table being slidable with respect to the magnet in a direction parallel to a longitudinal axis of the table; a drive configured to displace the table relative to the magnet; a lock configured to lock the table in a selected position relative to the magnet; the magnet being supported rotatably along a central horizontal axis of the transverse wall or column, the central horizontal axis of the transverse wall or column thereby defining an axis of rotation passing between the two poles of the magnet; a drive configured to rotate magnet about the axis; the table being connected to the magnet such that the table rotates with the magnet when the magnet rotates about said axis of rotation; the magnet and the table being configured to rotate from a position in which the poles and the table are substantially horizontal to a position in which the table and the poles are substantially vertical, and vice versa; and the rotation of the table and the magnet are locked together by the lock.
 2. The magnetic resonance imaging apparatus according to claim 1 in which the magnet generates a static magnetic field which permeates the patient-imaging space and which field is oriented perpendicular to the axis of the magnetic structure and perpendicular to the two poles and or the table.
 3. The magnetic resonance imaging apparatus according to claim 1, wherein the table is displaceable also in a direction transverse to its longitudinal axis, the extension of the displacement being limited to a distance which is equal to a width of the poles along the transverse direction or of a width of the table along the transverse direction.
 4. The magnetic resonance imaging apparatus according to claim 1, wherein the magnet and the table may be rotated from the substantially horizontal position to a position having an angle of less than 90° with respect to the horizontal position, and vice versa.
 5. The magnetic resonance imaging apparatus according to claim 1 in which the table and the magnet are rotatable from a position in which the table and the poles of the magnet are inclined at an acute angle relative to the horizontal into a position in which the table and the poles of the magnet are inclined at an acute angle with respect to the vertical.
 6. The magnetic resonance imaging apparatus according to claim 1, wherein the table is mounted on a pole of the magnet which is lower of the two poles when horizontal by first guides oriented in the longitudinal direction of the table and perpendicular to the axis of rotation of the magnet, in which first guides the table engages with complementary slides, and further comprising a motor engaged to a pinion which engages a rack which is parallel to the first guides.
 7. The magnetic resonance imaging apparatus according to claim 6, wherein the rack is integral with at least one of the slides of the table, while the pinion is housed in one of the guides.
 8. The magnetic imaging apparatus according to claim 6, further comprising second guides at opposite transverse ends of the pole to which the table is secured, the said second guides are oriented perpendicular to the first guides and parallel to the axis of rotation of the magnet, the first guides are engaged in the second guides by slides which are secured to the first guides while the table is displaced transverse to its longitudinal axis by a motor activating a pinion which engages a rack which is secured to the first guides and which is parallel to the second guides.
 9. The magnetic resonance imaging apparatus according to claim 8, wherein the rack is integral with at least one of the slides of the first guides, while the pinion is housed in one of the second guides.
 10. The magnetic resonance imaging apparatus according to claim 1, further comprising a footrest placed at an end of the table.
 11. The magnetic resonance imaging apparatus according to claim 1, wherein the footrest is hinged at the end of the table and is displaceable in an upright angular position where it extends perpendicular to the table and in an inactive position where it is parallel to the table and optionally forms a terminal prolongation of the table.
 12. The magnetic resonance imaging apparatus according to claim 1, further comprising a seat plate fixed to the table.
 13. The magnetic resonance imaging apparatus according to claim 12, wherein the seat plate is an intermediate section of the table which intermediate section has two opposite ends oriented transverse to the longitudinal axis of the table, each of the opposite ends being adjacent to the corresponding end of one first and one second part of the plate of the bed or of the table and which intermediate section is hinged at one end to the corresponding end of the first or second part of the plate of the bed or of the table in order to let the section being swingable between a position in which the section extends perpendicular to the plate of the bed or of the table and a position in which the said section extends in the same plane as the first and second parts of the bed or table while means are provided for locking the said section in each one of the two positions.
 14. The magnetic resonance imaging apparatus according to claim 1 in which the table has supporting legs with wheels in a region at one end thereof.
 15. The magnetic resonance imaging apparatus according to claim 1, further comprising a table supporting frame, which frame has supporting legs for supporting the table in a disengaged or extracted condition from the magnet, the frame having at least longitudinal guides which are coincident with the longitudinal guides for the slides of the table of the magnet and which are coincident with the longitudinal slides of the table, the bed or table supporting frame being freely movable independently from the magnet.
 16. The magnetic resonance imaging apparatus according to claim 1, further comprising a table supporting frame, which frame has supporting legs for supporting the table in a disengaged or extracted condition from the magnet, the frame having at least transverse guides which are coincident with the transverse guides for the slides of the table of the magnet and which are coincident with the transverse slides of the table, the table supporting frame being freely movable independently from the magnet.
 17. The magnetic resonance imaging apparatus according to claim 15, wherein the table supporting frame has a releasable lock for temporarily securing the table supporting frame to the magnet in a position of alignment of the longitudinal or of the transverse guides of the supporting frame with the longitudinal or with the transverse guides of the magnet.
 18. The magnetic resonance imaging apparatus according to claim 17, wherein when locked to the magnet, facing ends of the guides of the table supporting frame and of the guides of the magnet are at a distance one from the other which is smaller than a corresponding dimension of the table.
 19. The magnetic resonance imaging apparatus according to claim 1, wherein the table has a length which is greater than a corresponding dimension of the poles of the magnet and a width which is of the order of a corresponding dimension of the poles, the magnet being forming a patient imaging space which is at least shorter than a mean height of adult patients.
 20. The magnetic resonance imaging apparatus according to claim 1, wherein an axis coinciding with the central horizontal axis of the transverse wall or column is disposed within the patient-imaging space.
 21. The magnetic resonance imaging apparatus according to claim 1, wherein the central horizontal axis of the transverse wall or column is coincident with a center of symmetry of the transverse wall or column.
 22. The magnetic resonance imaging apparatus according to claim 1, further comprising a shaft about which the magnet rotates, said shaft defining a central shaft axis comprising said axis of rotation and said shaft axis being perpendicular to a magnetic field generated by said magnet. 